Embryology

Question 1

What is the neck developed from?

Answer 1

Branchial/pharyngeal arches

Question 2

What is the face developed from?

Answer 2

5 mesenchymal processes/prominences

Question 3

What is the skull developed from?

Answer 3

Mesenchyme in the head region of the developing embryo

Question 4

What is mesenchyme?

Answer 4

Embryonic connective tissue
Same properties as connective tissue
Develops into bone, cartilage, blood vessels etc

Question 5

How is mesenchyme formed?

Answer 5

Neural crest cells in the head and neck region mix with mesoderm = mesenchyme

Question 6

What is the role of somites in the development of head and neck?

Answer 6

Somites in head region of embryo help in cranial skeleton development

Question 7

What are pharyngeal/branchial arches?

Answer 7

Series of arches which develop around future mouth and pharynx

Question 8

How many branchial arches are there?

Answer 8

6 arches start to develop but arch 5 disappears

Left with 1, 2, 3, 4 and 6

Question 9

What embryological tissues make up the branchial arches?

Answer 9

Ectoderm = outside + clefts between arches
Mesoderm = middle = cartilage, muscles
Endoderm = inside = pouches between arches

Question 10

What nerve does the 1st branchial arch form?

Answer 10

Mandibular branch of trigeminal

Question 11

What nerve does the 2nd branchial arch form?

Answer 11

Facial

Question 12

What nerve does the 3rd branchial arch form?

Answer 12

Glossopharyngeal

Question 13

What nerve does the 4th branchial arch form?

Answer 13

Superior laryngeal branch of vagus

Question 14

What nerve does the 6th arch of the branchial arches form?

Answer 14

Recurrent laryngeal branch of vagus

Question 15

What type of innervation does the glossopharyngeal supply to the parotid salivary gland?

Answer 15

Parasympathetic

Question 16

What is the anterior belly of the digastric muscle innervated by?

Answer 16

Mandibular division of trigeminal nerve (V3)

Question 17

What is the posterior belly of the digastric muscle innervated by?

Answer 17

Facial nerve

Question 18

What other important structures develop from the branchial arches?

Answer 18

Tongue
Thyroid gland
Parathyroid gland
Part of the pituitary gland

Question 19

What are the 5 processes that the face develops from?

Answer 19

1 frontonasal process
2 maxillary processes
2 mandibular processes

Question 20

How does the nostril form?

Answer 20

Ectodermal thickening pushes nwards/invaginates to form the nasal pit

Question 21

How is the philtrum formed?

Answer 21

Medial nasal process grows downwards and laterally

Question 22

How is the palate developed?

Answer 22

Development of the philtrum = primary palate
Maxillary processes = 2 palatine shelves grow inwards
Palatine shelves meet in midline to form secondary palate

Question 23

How is the cranial vault (flat bones) formed?

Answer 23

Membranous bones = formed by membranous ossification calvaria

Question 24

How is the base of the skull (irregular bones) formed?

Answer 24

Bones formed by endochondral ossification

Question 25

How is the viscerocranium (skeleton of face) formed?

Answer 25

Partly from branchial arches and partly from sensory (special sense) capsules

Question 26

What age does the anterior fontanelle close?

Answer 26

1.5 years

Question 27

What is the reason for the sutures between skull bones being soft?

Answer 27

Allows deformation during passage through birth canal

Question 28

What happens in craniosynostosis?

Answer 28

When the skull fuses too early
Doesn’t leave room for the brain to grow
Misshapen skull

Question 29

What are sensory capsules?

Answer 29

Derived from mesoderm of somites in head and neck region
Preform in cartilage and ossify to form bones around sense organs (e.g. nose, eye, ear)
Partly base of skull, partly viscerocranium